Chemical Bonding Project

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Transcript of Chemical Bonding Project

Chemical Bonding By: Lindsay Hooks and Abby Kinlaw When different elements (different types of atom) react and combine to form a compound (new substance) chemical bonds must be formed to keep the atoms together. Once these atoms are joined together its usually difficult to separate them.

Explanation/Demonstration of Ionic BondingOr, they can transfer or accept electrons to form positive and negative ions and form an ionic bond. An ionic bond is formed by one atom transferring electrons to another atom to form oppositely charged particles called ions, which attract each other.

• Explanation/Demonstration of valence electrons and how they are related to each type of bondExplanation/DemonstrationAll atoms are made up of a positively charged nucleus surrounded by negatively charged electrons. The outermost electrons -- the valence electrons -- are able to interact with other atoms, and, depending on how those electrons interact with other the atoms, either an ionic or covalent bond is formed, and the atoms fuse together to form a molecule. Explanation/Demonstration of how periodic trends affect bonding (i.e. electronegativity/polarity)As you go across a period the electronegativity increases. The chart shows electronegativities from sodium to chlorine - you have to ignore argon. It doesn't have an electronegativity, because it doesn't form bonds. As you go down a group, electronegativity decreases. (If it increases up to fluorine, it must decrease as you go down.) In chemistry, periodic trends are the tendencies of certain elemental characteristics to increase or decrease as one progresses along a row or column of the periodic table of elements. All periodic trends of the chemicals are based on Coulomb's law F_C = \frac{k q_1 q_2}{d^2}. As distance from the protons in the nucleus to the valence electrons increases values associated with attributes such as electron affinity, ionization energy, and electronegativity decrease.• Explanation/Demonstration of Covalent BondingThe atoms can join together by sharing electrons in what is known as a covalent bond. A covalent bond is formed by two atoms sharing electrons so that the atoms combine to form molecules. The bond is usually formed between two non–metallic elements in a molecule. The two positive nuclei (due to the positive protons in them) of both atoms are mutually attracted to the shared negative electrons between them forming the covalent bond.Chemical Bonding Project Ionic Bondselements start with a balanced charge. That is, the number of positively charged protons equals the number of negatively charged electrons, resulting in an overall neutral charge. However, sometimes an element with only one electron in an electron shell will give up that electron to another element that needs only one electron to complete a shell. When that happens, the original element drops down to a full shell and the second electron completes its upper shell; both elements are now stable. However, because the number of electrons and protons in each element are no longer equal, the element that received the electron now has a net negative charge and the element that gave up the electron has a net positive charge. The opposing charges cause an electrostatic attraction that pulls the ions together tightly into a crystal formation. This is called an ionic bond.An example of this is when a sodium atom gives up its only 3S electron to fill the last shell of a chlorine atom, which needs only one more electron to become stable. This creates the ions Na- and Cl+, which bond together to form NaCl, or common table salt.Covalent BondsInstead of giving away or receiving electrons, two (or more) atoms may also share electron pairs to fill their outer shells. This forms a covalent bond, and the atoms are fused together into a molecule. An example of this is when two oxygen atoms (six valence electrons) encounter carbon (four valence electrons). Because each atom wants to have eight electrons in its outer shell, the carbon atom shares two of its valence electrons with each oxygen atom, completing their shells, while each oxygen atom shares two electrons with the carbon atom to complete its shell. The resulting molecule is carbon dioxide, or CO2.